Skip Navigation, or press ALT and K together and then press enter.Welcome to the OMC website. This site has been developed for both the visually impaired and non visually impaired. If you would like to use the visually impaired version of this site please go to, or press ALT and I together and then press enter

Irish Child Health Database - Peer Reviewed Papers

Database Search

You are here: Irish Child Health Database » Study Papers » Analytical Studies » Case Control Study
  • Does the angle of episiotomy affect the incidence of anal sphincter injury?

    Published in:

    BJOG: An International Journal of Obstetrics & Gynaecology, Vol: 113, Page: 190-194

    Publication Date:


    Aims & Objectives:

    The aim of this study was to quantify the relationship between precise angle of episiotomy from the perineal midline and risk of third-degree tear


    OBJECTIVE: Mediolateral episiotomy is associated with lower rates of significant perineal tears than midline episiotomy. However, the relationship between precise angle of episiotomy from the perineal midline and risk of third-degree tear has not been established. This study quantifies this relationship. DESIGN: Case-control study. SETTING: National Maternity Hospital, Dublin, Ireland. SAMPLE: One hundred primiparous women who had undergone right mediolateral episiotomy 3 months previously. METHODS: Two groups of primiparous women were compared. Cases had sustained clinically apparent anal sphincter injury during delivery, while controls had not. The angle of episiotomy measured from the midline was marked on a superimposed sheet of transparent plastic film and measured using a protractor. Data were analysed using Student's t test, chi-square test and logistic regression analysis. MAIN OUTCOME MEASURES: Angle of mediolateral episiotomy from the perineal midline. RESULTS: Fifty-four cases and 46 controls were assessed. Cases were more likely to have undergone assisted delivery and consequently to have been delivered by an obstetrician than by a midwife. The mean angle of episiotomy measured significantly smaller in cases (30 degrees, 95% CI 28-32 degrees) than in controls (38 degrees, 95% CI 35-41 degrees; P<0.001). Analysis showed a 50% relative reduction in risk of sustaining third-degree tear for every 6 degrees away from the perineal midline that an episiotomy was cut. CONCLUSIONS: These results show that a larger angle of episiotomy is associated with a lower risk of third-degree tear and mediolateral episiotomy incisions should be made at as large an angle as possible to minimise the risk of sphincter disruption.


    M. Eogan; L. Daly; P. R. O'Connell; C. O'Herlihy

    Study Type:

    Study Papers » Case Control Study » Analytical Studies


    Accession Number: 2009510688. Language: English. Entry Date: 20070413. Publication Type: journal article; research; tables/charts. Journal Subset: Biomedical; Peer Reviewed; UK & Ireland. Special Interest: Obstetric Care; Women's Health. Grant Information: Irish Health Research Board. No. of Refs: 21 ref. NLM UID: 100935741. 1470-0328 PMID: 16411997


    angle of episiotomy; -third-degree tear

    International Classification:

    Pregnancy, childbirth and the puerperium



    Republic of Ireland (Republic of Ireland)